It is well known to use pressure regulators in irrigation systems in order to provide substantially constant, regulated outlet pressure over a wide range of regulator inlet pressures, to thereby insure, for example, that a supply of water to a sprinkler or other irrigation device is maintained at a substantially uniform pressure. The need for such regulators is particularly acute in low pressure systems because even slight variations in pressure may cause much greater variations in water delivery than the same system operating at high pressure.
The assignee of this invention currently manufactures and sells fluid pressure regulators of the flow-through type, having an inlet at one end of a tubular housing and an outlet at the other end of the tubular housing. A valve or regulator seat is fixed within the housing and is adapted to be engaged by a tubular plunger which is spring-biased away from the seat (i.e., in the direction of fluid flow) so that under normal conditions, maximum flow through the regulator is permitted. In the event of a pressure surge, the plunger is moved by back pressure within a diaphragm chamber, against the action of an opposed coil spring (and against atmospheric pressure), toward the regulator seat to thereby decrease flow through the regulator until the pressure is reduced, at which point the plunger will stop or, if pressure decreases sufficiently, move upwardly away from the seat to thereby increase the flow. In this way, the regulator constantly seeks an equilibrium position to thereby maintain a substantially uniform outlet pressure. See, for example, U.S. Pat. Nos. 7,048,001; 5,875,815; and 5,257,646.
In a typical regulator assembly, the internal diaphragm is engaged and held in place by a cap (or components within the cap) or upper housing that is fastened to the housing body or lower housing. Typically, the cap is secured to the housing body (or lower housing) by four circumferentially-arranged screws. This method of fastening is advantageous in that the cap does not rotate relative to the housing during assembly, and thus, the exposed diaphragm edge is not disturbed. There is a disadvantage, however, in that assembly equipment designed to simultaneously apply and tighten plural screws is expensive and complex. There remains a need, therefore, for a pressure regulator housing coupling arrangement that is of relatively simple design which facilitates the assembly process without damaging the otherwise fragile regulator diaphragm.